Telephone system



Sept. 5, 1933.

F. s. IRVINE TELEPHONE: SYSTEM Filed March 18, 1931 000 0 o :4% dew, |3441 /04 g 2 Sheets-Sheet l /Nl/ENTOR 5. /RV/NE Byeyn A TTORNE Y Patented Sept. 5, 1933 1,925,696 l .TELEPHONE SYSTEM Frank. S. l"Irvine, Greenlawn .Nu Y., assignor to :Bell Telephone Laboratories,

Incorporated,

- NewYork, N. Y., a4 corporation-ofNew; York Application March 18,'1931. Serial No. .523,392

1sy claims. l (o1. 1ro- 27) This invention relates. to telephone systems and has for-itsV object to` increase the eliiciency of such systemsby reducing the number of uncompleted calls.

rIhe two chief'freasons for failure to lcomplete connectionsv are that the line is already busy or that the subscriber does notl answer. Where `the lineis vbusya second. call after a short kinterval will usually-be completed. .Where the call is not answered it may require..many trialsl before a response is received. 1 v

Inlaccordance with the present invention the application of ringing current-to the called line initiates the operation of a timing-arrangement associated with a link. in the connection. After a vpredetermined time elapseswithout a response on the cal-led line a signal isfdisplayed atan operatorsposition.. When the operator responds;

party and` any message which he may care tohave delivered. to the called subscriber.; When the called subscriber returns he lmay establisha connection with this-operator Aand be informed. of incoming calls received during .his absence.

The invention is capabley of a number of embodiments some of which are shownin thezdraw i-ngsrin which: l v y Y Fig. l'shows a portion of a telephonie connection cmployinglpanel type automatic switches;

Fig. 2 shows a portion of a. telephonie connecf tion employing step-by-step switches;

3 shows the form of the'rtimingarrangement for connection with/anal selector;

,Figs; 4, 5r and G'show forms. of the timing arrangement for connection with an. incoming selector, a connector.rswitchf'ora lmanual interoilice trunk., Fig. 4- employingya timing switch,

Fig. 5 is an interrupter mechanism, and, Fig. 6-

showing an arrangement 'inv .whichthe -dont answer= trunk is common to aVnumber-of. selector switches., A j

The incoming selector oflig.v 1. and, theconnector switch of 2 represent automatic equipmentoi the type disclosed in the patent =to C. H. Berry, No. l,658,829,fgranted IFebruary 14, 1928 and in pages 53, to' 62. lof the second edition of Automatic Telephony `by `Smithvvand Campbell.'

Either lig. 1 or Fig. 2fmay `leefconnected with any one of Eig-5.145 andvG, while Fig. 3. can-onlybe connected with Fig. 1. The preferr'edembodimentor, the invention. is-represente'dby theicomv binationot Fig. 1 with Fig. 4... A somewhat simi- I lar arrangement .in -which thek dont answer" trunk is individual tothe called line is disclosed and claimed in the copending vapplication of E. E'. Hinrichsen,.Serial 100.623,388, filed Mar. 18r 1931.

The preferred embodiment oi the invention will 6orst be described. The establishment of a connection from a callingsubstation 1.00 toa vcalled substation 101. by-means of .paneltype switches is well known in the art. Such a connectionr will include a line iinde1h102,` an incoming selector 103 andfa final lselector 104. When the called line has been selected,y tested and found idle, the final .selector sequence switch` is advanced to position 13. andr the incoming` selectorr sequence switch is advanced `toposi-tion 12. Inthis positiona ringing. circuit-is establishedl from ringing source 105., righty contact .of cam 106,9through the windingrof relay 107, lower leftf-andupper 'right` contacts `of cam `108, ring-brush of the` incoming selector 103, contactsof cam 109, ring brush kof the nalselector- 104, throughy the subscribers substation ringer back to thevtip brush of` the iinalselector 104,.contacts.of cam 110, tip brush of `incoming selectorl, lower contact of cam 111, to ground." IThe subscribers bellis given along steadyring in this circuit while .the incoming. selectorsequence.switch is advanced. under the control of an interrupter to position -14 Where the ringing ,interrupter 112 isincluded in the ringing circuit. If the subscriber answersl he 80 completes a direct currentccircuit for relay 107, which further advances the sequencefswitch to disconnect ringing current from the line.and tov establish the talking circuit. Y

During.` the time `thatringing current is bei-ng applied to the called line, the dont answer apparatusis functioning. kWhen the incoming se*- lector sequence switchv reaches position 12',. ground-is connected over the contacts of cam 113, to conductor 424 vand the winding. of relay-'410'. Relay 410 operates and prepares a circuit `for relay 412. Conductors 414 and 415 are connected in multiple with'the tip and ring conductors .of the established:A connection at the brushes of the incoming selector.'` Therefore 'when ringing current is applied to thecalled line it alsoV ilows over conductor 415, inner back contact offrelay 41'1', throughv condenser 41?, Winding of relay 412, front contact of relay 410,` outer back contact-fof; relay g 4111. and-conductorr4l4 Relay 412 respondsto .10 thelapplication-ofv ringing cu-rrent,` and in so' docloses a circuit forrnagnetv i406 of the timing :inviten-400. Each time that ringing currentv is interruptedgimagnet y4062 releases. and steps' .the timingswitcb onezstep. If: the subscriber .an.`r

A SequeIlCG v phone and the calling line.

swers while the timing switch 400 is operating, the advance of the incoming selector switch will release relay 410 and open the circuit of relay 412. If the subscriber fails to answer, after a predetermined number of steps have been taken a circuit is closed from battery through the winding of relay 411, brush 402, and the terminal on which it is resting, to ground. Relay 411 locks over its right contact and brush 401 to the grounded offnormal contact. It also transfers conductors 414 and 415 over brushes 404 and 403 to the tip and ring contacts of jack 416. A circuit is also closed in this position of switch 400 from ground at the back contact of relay 417 over brush 405 to lamp 418 and battery. Lamp 413 lights as a signal to the dont answer operator.

This operator is equipped with cord circuits having a resistance 419 bridged across the tip and ring conductors over the back contacts of relay 420. The insertion of plug 422 in jack 416 connects resistance 419 in series with relay 107 at the incoming selector. Relay 107 operates in this direct current circuit and establishes the talking circuit in the usual manner. The insertion of plug 422 in jack 416 also closes Va circuit from ground over the sleeves of the plug and jack through the winding of relay 417 to battery. Relay 417 operates, opening the circuit of lamp 418 and also opening the restoring circuit of switch 400. The operator on seeing lamp 418 go out closes key 421 thereby operating relay 420 and establishing a talking circuit between her tele- The inclusion of condenser 423 in this talking circuit prevents the operation of supervisory relay 114 at the incoming selector. After the operator has ascertained the identity of the calling and called subscribers and any message which the calling subscriber wishes to have delivered, she removes plug 422 from jack 416 releasing relay 417. The advance of the incoming selector sequence switch to talking position has already opened the circuit of relay 410 so that a circuit is now closed from ground over the oir-normal contact of brush 401, back contact of relay 410, right back contact of relay 417, back contact and winding of magnet 406 to battery. Magnet 406 interrupts its own circuit to advance the timing switch 400 to its normal position where the operating circuit oi1 magnet 406 and the locking circuit of relay 411 are opened, restoring the dont answer apparatus to normal.

The manner of using the dont answer apparatus in connection with a step-by-step connector switch will be apparent from a consideration of Fig. 2. In `accordance with the usual operation of step-by-step apparatus, lfollowing the selection of a called line by a connector switch 200, a relay such as relay 205 is operated and connected in a circuit for testing whether the Ycalled line is busy or idle. If the line is idle relay 205 releases and a relay such as relay 204 is operated to establish the ringing circuit. Relay 204 locks under the control of the calling subscriber. When re1ay'204 operates 'the ringing circuit is closed from ringing source 202 through the interrupter 203, lower winding and outer lower back` Contact of relay 201, outer lower front contact of relay 204 to the ring brush of the connector 200, through the subscribers substation ringer to the tip brush of the connector 200, upper front contact of relay 204 to ground at the upper back contact of relay 201. When relay 205 closes its back contact it connects ground over its back contact and the inner lower-back contact of relay 201 to conductor 424 operating relay 410. Conductors 414 and 415 are connected in multiple to the tip and ring conductors of the connector circuit so that the operation'of relay 204 also connects them to the source of ringing current 202. rllhe response of the called subscriber causes the operation of relay 201 which locks to holding ground and opens the circuit of relay 410. The operation of the dont answer apparatus is the same as previously described so that, if the subscriber has not answered when brush 402 reaches its grounded terminal, relay 411 operates to connect the connector switch with jack 416 and lamp 418 is lighted to signal the operator. As before the insertion of plug 422 in jack 416 provides a direct current circuit for the tripping relay, in this case relay 201, which operates and .locks as on the response of the subscriber. The release of relays 201 and 204 is under the control of the calling subscriber and the restoration of the timing circuit is under the control of the operator.

If it is desired to associate the dont answer equipment with nal selectors, the circuit must be slightly modied as shown in Fig. 3. When the final selector sequence switch reaches position 13,-in which position the ringing circuit is established, a circuit is closed from ground over cam 115, conductor 324, winding of relay 310 to battery. Relay 310 prepares the ringing circuit 105 from the tip brush of the final selector 104, conductor 314, outer right contact of relay 310, outer back contact of relay 311, condenser 313, winding of relay 312, right back Contact of relay 317, inner back contact of relay 311, inner right con- 110 tact of relay 310, conductor 315 to the ring brush of the nal selector 104. `Relay 312 responds to the impulses of ringing current and closes a circuit from ground over its front Contact to the Winding of magnet 306. At the end of each im- 1 1 pulse magnet 306 releases, advancing the timing switch 300 one step. If the called subscriber' answers before the predetermined time interval has elapsed, relay 107 willfunction as previously described to remove ringing current from the line. Impulses of battery are connected by the ringing machine to conductor 325 in synchronism with the ringing current. These impulses areinefective as long as the ringing current is being received, but with ringing current out oi 125 by relay 107, relay 312 is not operated and a circuit is closed during the next ringing interval from battery over conductor 325, inner left front contact otrelay 310, normal contact and left winding of' relay 317, over the normal Contact 130 of brush 301 and the outer left front contact or" relay 310 or over the oli-normal Contact of brush 301 to ground at the back Contact of relay 312 dependent upon whether switch 300 has advanced from normal. Relay 317 operates, locking. to battery at its alternate contact and opening the ringing bridge across the talking` conductors. When the connection has been released, the nal selector sequence switch leaves position 13 and relay 310 releases. If switch 300 has not stepped 149 off-normal, this immediately releases relay 317. If the selector is in any other position, a circuit is closed from ground at the back contact of relay 312, oir-normal terminal of brush 301, back contact of relay 310, back contact and winding of M5 magnet 306 to battery. Magnet 306 restores switch 300 to its normal position where relay 317 releases.

If the called subscriber does not answer, when brush 301 reaches its grounded terminal an obl5@ vious circuit is closed. for. relayll. Relay 311 disconnects .theringing bridge and'connects condoctors 314 and 315 to the tip and ring contacts of jack .816. Inthis position 'af circuit .is also closed for lamp 31.8'over brush 30:5 .and the back contact of relay 317. When the operator observes that lamp 318 is lighted, she inserts plug l3.22 in jackflo kconnecting resistance 319 across the. talking circuit to operate relay 107 and' disconF Vneet the ringing current. The'operation of key 321 extends the talking circuit to her headset. The insertion of plug 322 connects groundl over the sleeves of plug 322 and jack .316. and the right winding of relay 317 to battery. Relay '317'. locks in a circuit from battery over its alternate contact and left winding, off-normal .contact .of brush 301 to ground at the back contact of relay 312, extinguishing lamp 318 and further opening the ringing bridge. After the `l.operatorz'hasattended to the Wants of the calling subscriber, the removal of plug 322 is ineffective, relay 3171remaining locked underfthe control of the calling subscriber. The release of the circuit is the same as above described.

The modification of the dont answer equip.-v ment shown in Fig. 5 depends for its timing upon two' related interrupters instead of upon'the ringing current. The connection of ground to conductor 424 in this instance operates relayv 510 which extends the circuit controlled by interrupiters'525 and 526' to relays A527 and 528fand also provides locking ground for those relays. When interrupter 525 closes its contact, a circuit is completed from ground over interruptor 525, inner left contact of relay 510, back contact of .relay 528, winding of relay 527 to battery. Relay 527 closes a holding circuit for itself over the back Contact of relay 528, outer left contact of relay 527', to ground at the right contact of yrelay 510. A measured'interval thereafter interrupter 526'closes a circuit from ground over its contact, over the outer left contact of relay l510, inner leit vcontact of relay 52:7, to the winding of relay 528 and battery. Relay528 locks directly to the contact of relay 510 and opens the holdingcircuit oi relay 527. When relay 527, which is slow to release, closes itsback contact, vit completes a circuit from battery through the lamp 518, 4inner front contact of relay 528, inner back contact of relay 527, to ground at'the back contact of relay 517, lighting the lamp as a signal tothe operator.. With relay 527 released and relay 528 operated, conductors 414 and'415 are extended to the tip and ring of ja'cl:I 516. `Theresponse of the operator, by'inserting plug 522 in jack`5l6, operates relay 517 extinguishing lampv 516 and providing a substituteholding circuit'for relay 528. The advance oik the incoming selector se@ quence switch as previously described, releases relay 510, but relay 528 remains operated underthe'control of the operator. When the operator removes plug 522 the dont answer. equipment is completely restored to normal.

The modication of the dont.ansWer-. equipe ment shown in Fig. 6 is intended for use'in com mon With a number oli" incomngselectors and employs switch 600 as ander switch instead of a timing switch, the timing function being carried outby interrupters' 625 and 626. When the incoming selector reaches-its ringingy position and connects ground to conductor 424,- a cire cuit is completed over the back contact ofl relay 629through the Winding-of vrelay f 610 to battery. Relays 629 and 610 are individual-to the incorning selector,` while the remaining. equipment-is' Aates to restorethe nder switch to normal.

common tol aplurality of selectors. 'Relay .610 closes an obvious circuit for relay 630 and connects battery through resistance 633 to the terminafl offbrush 6.0.2 corresponding to this incoming .selector in :the `back of switch 60.0. .Relay 630 closesa circuit from ground. over its left contact, back .contact of relay 631, backcontact and Wind i-ng of' magnet .6.06 to battery. Magnet 606 op-v eratesin this selfeinterrupting circuit to' advance switch .6.00 in. search of the incoming selector over Awhich theI call is being extended. When this selector is found, a circuit is completed from .battery-'over :brush 602 through the winding of relay. 63.1 to ground at the front contact of relay 630. Relay 6.31 operates in this circuit, 'opening the. circuit of magnet 606 and connecting ground throughresistance 634 to brush 602 to reduce the potential-on the terminal which the brush is engaging to mark it as busy.v It also closes a circuit from ground at the front contact of rrelay 630 over its right front contact through the Winding of relay 6.32. Relay 632 operates and prepares ,a circuit for relay 627. When interruptor 625. closesV its contact the circuit offrelay `627 is extended over the back contact of relay 628, inner left contact of relay 632 to ground at the interrupter 625. VRelay .627 closes a holding circuit Afor itself over the back contact of relay 62.8, outer left contact of relay 627 to ground at the right contact of relay 632. A measured interval thereafter, interruptor 626 closes a circuit fromground over its contacts, outer left contact ofv relay 6.32, inner. left contact of relay 627, winding of relay 628, to battery. i Relay 628 locks to ground atvth'e right contact of relay 632. It also opens the holding circuit of relay 627 which,

being slow to release, closes its back contact after an additional interval `extending conductors414 and 415 over brushes 6.04 and 603, backfcontacts of relay 627, front contacts of relay 628 to jack 616. Relay 6 27 also .closes a circuit from battery through lamp 618, inner right front contact of relay 628, inner right back contact of relay 627 to ground at the inner back contact of relay 617, lighting the lamp as a signal tothe. operator.

When the operator responds, the ringing current is cut oil by` relay 107 and the incoming selector sequence switch is advanced soy that relay 610 is released, in turn releasing` relays 630, 681 and 632. Ground onthe sleeve of plug 622 operates relay 617 which opens the restoring circuit ofthe nder 600, closes a circuit over brush 605 for relay 629 to immediately release relay y610 and provides a v.substitute holding circuit for relay 628.y When the operator has recorded any `message delivered by the calling subscriber, she

removes plug 622, releasing relay 617 to complete a circuit from ground overfthe back Contact of relay 617, back contact of relay 630, oi-normal terminal of brush 601, back contact andwinding of magnet 606 to battery. `Magnet 606 VVoper- If the callingsubscriber releasesror the called subscriber answers before the lamp 618 is lighted, relay 610 is released as abovedescribed and, since relay 617 has not been operated, the nder is immediately restored to normal. The-finder switch 600 is, of course,fnot limited to the number of terminals shown, but may be of any convenient size. Likewise a plurality 'of the circuits maybe furnished to serve larger groups of selectors.

Although in the case of manual connections supervision' by the operatorrenders any sort of dont answer-service more orless unnecessary it is apparent2 that the equipment is readily adaptable for use with interoince or interposition trunks.

What is claimed is:

l. In a telephone system, a calling line, a called line, means to establish a connection from said calling line to the terminals'of said called line, a scource of ringing current, a timing device associated with said connecting means, means simultaneously eiective to apply ringing current from said source to said called line and to start said timing device, an operators position, a signal thereat, and means under the control of said.

timing device to extend said calling line to saidv operators position and to operate said signal.A

2. In a telephone system, a calling line, a called line, means to establish a connection from said calling line to the terminals of said called line, a source of ringing current, a timing device associated with said connecting means, means simultaneously effective to apply ringing current from said source to said called line and to start said timing device, an operators position, a signal thereat, means under the control of said timing device to extend said calling line to said operators position and to operate said signal, and means under the control of the called line prior to the completion of said predetermined time to prevent the extension of said calling line to said operators position.

3. In a telephone system a calling line, a called line, an operators position, a signal at said position, means to establish a connection from said calling line to the terminals of said called line, means to apply ringing current to said called line, means associated with said connecting means responsive to said ringing current to measure a predetermined time, means effective at the end of said time to operate said signal, and means to connect said calling line with said operators position.

4. In a telephone system, a calling line, a called line, an operators position, a cord circuit, a jack and a signal at said position, means to establish a connection from said calling line to the terminals of said called line, means to apply ringing current to said called line, means responsive to said ringing current to measure a predetermined time, means effective at the end of said time to connect said calling line with said jack, means to operate said signal, and means responsive to the connection of said cord circuit with said jack to disconnect said ringing current from said called line. v

5. In a telephone system, a calling line, a called line, means including a plurality of conversational links for establishing a connection from said calling line to the terminals of said called line, means to apply ringing current to said called line, means individual to one of said links responsive to said ringing current to measure a predetermined time, and means effective at the end of said time to operate a signal.

6. Ina telephone system, a calling line, a called line, means to establish a connection from said calling line to the terminals of said called line, means to apply ringing current to said called line, a stepping switch, means responsive to said ringing current to step said switch to measure a predetermined time, and means effective at the end of said time to operate a signal.

'7. In a telephone system, a calling line, a called line, means to establish a connection from said calling line to the terminals of said called line, means to apply ringing current to said called line, a stepping switch means responsive to said ringing current to step said switch and means effective in a predetermined position of said switch to operate a signal.

8. In a telephone system, a calling line, a called line, an operators position, a signal at said position, means to establish a connection from said calling line to the terminals of said called line, means to apply ringing current to said called line, a stepping switch, means responsive to said ringing current to step said switch, and means effective in a predetermined position of said switch to operate said signal.

9. In a telephone system, a calling line, a called line, an operators position, a signal at said position, means to establish a connection from said calling line to theterminals of said called line, means to apply ringing current to said called line, a stepping switch, means responsive to said ringing current to step said switch, and means effective in a predetermined position of said switch to operate said signal and to connect said calling line with said operators position.

10. In a telephone system, a calling line, a called line, means to establish a connection from said calling line to the terminals of said called line, an operators position, a cord circuit, jack and signal at said position, means to apply ringing current to said called line, a stepping switch, means responsive to said ringing current to step said switch, means effective in a predetermined position of said switch to'connect said calling line with said jack and to operate said signal, and means responsive to the connection of said cord circuit with said jack to disconnect said ringing current from said called line. v

1l. In a telephone system, a calling line, `a called line, means to establish a connection from said calling line to the terminals of said called line, an operators position, a cord circuit, jack and signal at said position, means to apply ringing current tosaid called line, a stepping switch, means responsive to said ringing current to step said switch, means effective in a predetermined position of said switch `to connect said calling line with said jack and to operate said signal, means responsive to the connection of said cord circuit with said jack to disconnect said ringing current from said called line, and means responsive to the disconnection of said cord circuit from said jack to restore said stepping switch.

12. In a telephone system, a calling line, a calledline, means including a plurality of conversational links for establishing connection from said calling line to the terminals of said called line,v means to apply ringing current to said called linea stepping switch individual 'to one of said links, means responsive to said ringing current to step said switch, and means effective in a predetermined position of said switch to operate a signal. V

13. In a telephone system, a calling line, a

- called line, means including a plurality of selector switches for establishing a connection from said calling line to the terminals of said called line, means to apply ringing current to said called line, means individual to one of said selector switches responsive to' said ringing current to measure a predetermined time, and means effective at the end of said time to operate a signal.

14. In a telephone system, a calling line, a called line, means including an incoming selector circuit for establishing a connection from said calling line to the terminals of said called line, means in said incoming selector circuit to apply ringing current to said called line, means individual to said incoming selector circuit respon-` sive to said ringing current to measure a predetermined time, and means effective at the lend of said time to operate a signal.

15. In a rtelephone system, a calling line, a called line, means including an incoming selector circuit for establishing a connection from said calling line to the terminals of said called line, means in said incoming selector circuit to apply ringing current to said called line, a stepping switch individualto said incoming selector circuit, means responsive to said ringing current to step said switch and means effective in a predetermined position of said switch to operate a signal. 16. In a telephone system, a c allingline, a called line, means to establish a connection from said calling line to the terminals of said called line, a source of ringing current, a timing device comprising a plurality of interrupters, means simultaneously eiective' to apply ringing current from said source to said called line and to render said timing device effective, an operators position, a signal thereat, and means controlled by the successiveoperation of saidY interrupters to operate said signal and to extend said calling line to said operators position.

17. In a telephone system, a calling line, a called line, a plurality of selector switches, means including one of said selectorr switches to establish a connection from said calling line to the terminals of said called line, a sourceof ringing current, a timing device common to said plurality of selector switches, means simultaneously efline to said operators position and to operate,

said signal.

18. In a telephone system, a calling line, a

called line, a plurality of selector switches, means including one of said selector switches to-establislfiV a connection from said calling line to the terminals of said called line, a source of ring-` ing current, a timing device common to said plurality of selector switches, means simultaneously effective to apply ringing current -from said source to said called line and to cause the association of said timing device' with said one selector switch, means responsive to the association Y of said timing device with said selector switch to start the timing operation, an operators position, a signal thereat, means under the control of said timing device to extend said calling line to said operators position and to operate said signal, and means under the control of the called line prior to the completion of said timing operationsimultaneously eiective to disconnect said ringing current and to disconnect saidtiming `device from said selector switch..

FRANK s. IRVINE. 

